Powered conveyors for moving granular material are configured in any of a wide variety of types. Examples include generally-flat belt conveyors (either horizontal or inclined), inclined ladder conveyors equipped with protruding paddle-like flights and auger conveyors, sometimes known as screw conveyors. Often, the area immediately above the conveyor is unobstructed and the material being conveyed need not pass through any type of restriction. However, not all coveyors function in such an operating environment.
An example is the conveying system on an agricultural machine known as a combine. A combine might be termed a "cutting-and-threshing" machine in that it cuts a plant stalk and then threshes such stalk to separate the desired grain from the associated stalk or plant portion. Combines are used to harvest, e.g., soybeans, corn, wheat and rice, and the leading manufacturer of such machines is Case Corporation of Racine, Wis.
Stalk threshing is by a rotating perforated drum and when the grain is separated, it falls through the openings in the drum onto an apron-like trough. An open-top conveyor (e.g., a screw-like auger conveyor) operates along the length of the trough to move the grain out of the trough and through a tube to another conveyor. The second conveyor deposits the grain in a bin on the combine for later transfer to a haulage wagon or the like.
While the foregoing arrangement generally works well, it is not without its problems. A significant problem arises from environment in which the first conveyor is required to operate. Such first conveyor is "open-topped" along much of its length so that grain falling through the threshing drum may fall freely onto and flow into such conveyor for grain movement. However, toward it discharge end, such conveyor is required to urge the grain into and through a restricting tubular guide portion which "focuses" the grain flow to the second conveyor.
The abruptness of the restriction impedes free movement of grain. Grain is thereby caused to "bunch" or deflect at that location and the smooth forward progress of grain movement is impeded. As a result, the efficiency of the conveying arrangement is adversely affected.
Increasing the speed of the conveying arrangement seems to do little if anything to improve conveying rate. In a specific embodiment, the drive speed of the arrangement was increased about 15% and the amount of corn conveyed thereby actually decreased slightly. (In other embodiments, an increase in drive speed did produce a modest increase in the rate at which grain was conveyed.)
An apparatus which resulted in higher conveyor output without increasing drive speeds, which is easy to fabricate, which is low in cost and which can be retrofitted to certain existing combines would be an important advance in the art.